The present invention relates to a method for acid eluting a uranyl carbonate-loaded, anionic exchange resin and more particularly, relates to a method for directly eluting a uranyl carbonate-loaded anionic resin with a concentrated acidic eluant without preconditioning and/or post conditioning the resin.
In a typical leach operation, a mineral bearing ore is contacted with a leach solution to dissolve the mineral values, e.g. uranium, from the ore. The uranium is then concentrated from the relatively dilute leach solution by passing the leach solution through an ion exchange medium which adsorbs the uranium from the leach solution. Where a carbonate solution is used as the leach solution, the uranium will exist in the leach solution in the form of uranyl carbonate complexes which exchange readily with strong basic anionic resins. In the majority of the known commerical leach operations of this type, these resins when sufficiently loaded with uranium are eluted with concentrated carbonate/bicarbonate solutions and/or chloride solutions, e.g. sodium or ammonium chloride.
Although acidic eluants would appear to offer many advantages in most leach operations, as far as known, they are not used in known commercial operations which utilize a carbonate leach solution. Previous known suggestions that acidic eluants could be used in carbonate leach operations also indicate that the loaded resin has to be first preconditioned before eluting with acidic eluant and/or that the resin has to be post-conditioned after elution before the resin undergoes its next loading cycle, see U.S. Pat. No. 2,811,412. Further, it is a commonly-held belief in the art, that the carbon dioxide which would be generated by directly eluting a uranyl carbonate-loaded resin with an acidic eluant could cause serious disruption of the ion exchange column operations and could cause rupture, and hence, destruction of the expensive resin beads; see Merritt, R. C.; THE EXTRACTIVE METALLURGY OF URANIUM, Colorado School of Mines Research Institute, 1971, page 161.